• Standard Multi Ratio Current Transformer Taps
• Standard Accuracy Class
• Standard 5A Secondary CT Burden
• Standard Burdens At 60HZ

IEEE Standard Ratings
Standard multi-ratio current transformer taps
Current and voltage transformers (CTs and VTs)









IEEE C57.13-2016, Table 11: Standard multi-ratio current transformer taps*

600:5
1200:5
2000:5
3000:5
4000:5
5000:5

Ratio
Tap
Ratio
Tap
Ratio
Tap
Ratio
Tap
Ratio
Tap
Ratio
Tap
50:5
X2-X3
100:5
X2-X3
300:5
X3-X4
300:5
X3-X4
500:5
X1-X2
500:5
X2-X3
100:5
X1-X2
200:5
X1-X2
400:5
X1-X2
500:5
X4-X5
1000:5
X3-X4
1000:5
X4-X5
150:5
X1-X3
300:5
X1-X3
500:5
X4-X5
800:5
X3-X5
1500:5
X2-X3
1500:5
X1-X2
200:5
X4-X5
400:5
X4-X5
800:5
X2-X3
1000:5
X1-X2
2000:5
X1-X3
2000:5
X3-X4
250:5
X3-X4
500:5
X3-X4
1100:5
X2-X4
1200:5
X2-X3
2500:5
X2-X4
2500:5
X2-X4
300:5
X2-X4
600:5
X2-X4
1200:5
X1-X3
1500:5
X2-X4
3000:5
X1-X4
3000:5
X3-X5
400:5
X1-X4
800:5
X1-X4
1500:5
X1-X4
2000:5
X2-X5
3500:5
X2-X5
3500:5
X2-X5
450:5
X3-X5
900:5
X3-X5
1600:5
X2-X5
2200:5
X1-X3
4000:5
X1-X5
4000:5
X1-X4
500:5
X2-X5
1000:5
X2-X5
2000:5
X1-X5
2500:5
X1-X4
5000:5
X1-X5
600:5
X1-X5
1200:5
X1-X5
3000:5
X1-X5

*Contact factory for customer specific ratio taps.



Standard accuracy class for
IEEE C57.13-2016, Table 8: Standard accuracy class for metering service and 
corresponding limits of transformer correction factors*


Voltage Transformers 
Current Transformers


90% to 100% rated voltage 
100% rated current+ 
10% rated current 
5% rated current

Accuracy

class
Min
Max
Min
Max
Min
Max
Min
Max
0.15S
-
-
0.9985
1.0015
-
-
0.9985
1.0015
0.15
0.9985
1.0015
0.9985
1.0015
-
-
0.9970
1.0030
0.3S
-
-
0.9970
1.0030
-
-
0.9970
1.0030
0.3
0.9970
1.0030
0.9970
1.0030
0.9940
1.0060
-
-
0.6
0.9940
1.0060
0.9940
1.0060
0.9880
1.0120
-
-
1.2
0.9880
1.0120
0.9880
1.0120
0.9760
1.0240
-
-

*Other accuracy requirements may be specified and should be included on the 
nameplate.
+For current transformers, the 100% rated current limit also applies to the 
current corresponding to the continuous thermal current rating factor.

Standard VT burdens at 60 Hz



Standard 5A secondary CT burden


IEEE C57.13-2016, Table 10: 
Standard 5A secondary CT burdens*


 Burden
designation

Resistance
(ohms)

Inductance
(millihenrys)

Impedance
(ohms)

Volt-
amperes

Power
factor

Metering burdens
E-0.04+
0.04
0.0
0.04
1.0
1.0
E-0.2+
0.20
0.0
0.20
5.0
1.0
B-0.1
0.09
0.116
0.1
2.5
0.9
B-0.2
0.18
0.232
0.2
5.0
0.9
B-0.5
0.45
0.580
0.5
12.5
0.9
B-0.9
0.81
1.040
0.9
22.5
0.9
B-1.8
1.62
2.080
1.8
45.0
0.9

Relaying burdens
B-1
0.5
2.3
1.0
25
0.5
B-2
1.0
4.6
2.0
50
0.5
B-4
2.0
9.2
4.0
100
0.5
B-8
4.0
18.5
8.0
200
0.5




IEEE C57.13-2016, Table 19:
 
Standard VT burdens

 at 60 Hz


Burden
designation
Secondary

volt-amperes
SecondaryBurden

power factor
W
12.5
0.10
X
25.0
0.70
M
35.0
0.20
Y
75.0
0.85
Z
200.0
0.85
ZZ
400.0
0.85